As a refrigerant evaporator, a multi-flow type heat exchanger is described in U.S. Pat. No. 6,339,937 (JP 2001-324290A) or a serpentine-type heat exchanger is described in JP 2001-12821A, for example. In this case, when a core width dimension of an evaporator is reduced in order to reduce the size or the weight of the evaporator, a refrigerant passage sectional area is reduced. For example, when a tank sectional area and a tube thickness dimension are reduced, a pressure loss is increased in the refrigerant evaporator. Therefore, a refrigerant distribution performance is deteriorated, and an air temperature flowing from the refrigerant evaporator becomes ununiform.
Further, in a multi-type refrigerant evaporator described in JP 2001-343174, at least two refrigerant inlets are provided in a refrigerant inlet tank. However, in this case, a piping structure for introducing the refrigerant to the refrigerant inlets becomes complex, and a dead space becomes larger. Therefore, manufacturing steps become complex.
In contrast, in a whole-pass type refrigerant evaporator (one pass type), it is difficult to improve a refrigerant distribution performance with a simple structure.